1. Field of the Invention
This invention relates to kinase inhibitors, pharmaceutical compositions containing the inhibitors, and methods for preparing these inhibitors. The kinase inhibitors of this invention are useful for the treatment of inflammation, osteoarthritis, rheumatoid arthritis, cancer, autoimmune diseases, and other cytokine-mediated diseases.
2. Description of the State of the Art
A number of chronic and acute inflammatory conditions have been associated with the overproduction of pro-inflammatory cytokines. Such cytokines include but are not limited to tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), interleukin 8 (IL-8) and interleukin 6 (IL-6). Rheumatoid arthritis (RA) is a chronic disease where TNF-α and IL-1β are implicated in the onset of the diseases and in the progression of the bone and joint destruction seen with this debilitating condition. Recently approved therapeutic treatments for RA have included soluble TNF-α receptor (ENBREL™) and IL-1 receptor antagonist (ANAKINRA™). These treatments work by blocking the ability of their respective cytokines to bind to their natural receptors. Alternative methods for treating cytokine-mediated diseases are currently under investigation. One such method involves inhibition of the signaling pathway that regulates the synthesis and production of pro-inflammatory cytokines such as p38.
P38 (also known as CSBP or RK) is a serine/threonine mitogen-activated protein kinase (MAPK) that has been shown to regulate pro-inflammatory cytokines. P38 MAPK was first identified as a kinase that becomes tyrosine phosphorylated in mouse monocytes following treatment with lipopolysaccharide (LPS). A link between p38 MAPK and the response of cells to cytokines was first established by Saklatvala et al., (Cell, 1994, 78:1039-1049), who showed that IL-1 activates a protein kinase cascade that results in the phosphorylation of the small heat shock protein, Hsp27, probably by mitogen-activated protein activated protein kinase 2 (MAPKAP kinase-2). Analysis of peptide sequences derived from the purified kinase indicated that it was related to the p38 MAPK activated by LPS in mouse monocytes (Han, J., et al., Science, 1994, 265:808-811). At the same time it was shown that p38 MAPK was itself activated by an upstream kinase in response to a variety of cellular stresses, including exposure to UV radiation and osmotic shock, and the identity of the kinase that directly phosphorylates Hsp27 was confirmed as MAPKAP kinase-2 (Rouse, J., et al., Cell, 1994, 78:1027-1037). Subsequently, it was shown that p38 MAPK was the molecular target of a series of pyridinylimidazole compounds that inhibited the production of TNF from LPS-challenged human monocytes (Lee, J. et al., Nature, 372:739-746). This was a key discovery and has led to the development of a number of selective inhibitors of p38 MAPK and the elucidation of its role in cytokine signaling.
It is now known that multiple forms of p38 MAPK (α, β, γ, δ), each encoded by a separate gene, form part of a kinase cascade involved in the response of cells to a variety of stimuli, including osmotic stress, UV light, and cytokine mediated events. These four isoforms of p38 are thought to regulate different aspects of intracellular signaling. Activation of p38 is part of a cascade of signaling events that lead to the synthesis and production of pro-inflammatory cytokines such as TNF-α. P38 functions by phosphorylating downstream substrates that include other kinases and transcription factors. Agents that inhibit p38 MAPK have been shown to block the production of cytokines including but not limited to TNF-α, IL-6, IL-8 and IL-1β in vitro and in vivo models (Adams, J. L., et al., Progress in Medicinal Chemistry, 2001, 38:1-60).
Abl (also known as Ableson) is a tyrosine kinase that is expressed in hematopoietic cells and is implicated in the progression of various liquid tumors including chronic myeloid leukemia (CML) and acute lymphoblastic leukemia (ALL). Transformation is a result of a chromosomal translocation, known as the Philadelphia chromosome. This leads to a constitutively activated chimera between Ableson and the breakpoint cluster region (BCR)—the Abl-BCR protein. GLEEVEC®, also known as Imatinib (Novartis) is a potent inhibitor of Abl and is currently used to treat CML patients (N. Engl. J. Med., 2001, 344:1031-1037). This drug has become the standard of care for this deadly disease and is also being looked at in a variety of other cancer settings including gastrointestinal stromal tumors (GIST).
There is evidence that fibroblasts respond to the growth factor protein TGF-β by stimulating the Abl pathway and lead to morphological changes indicative of fibrosis; therefore Abl could play a role in the pathogenesis of fibrotic diseases like idiopathic pulmonary fibrosis. Leof et al. (J. Clin. Invest., 2004, 114(9) 1308-1316) have demonstrated pre-clinical efficacy of GLEEVEC® in a bleomycin-mediated model of lung fibrosis in mice. GLEEVEC® is being evaluated in patients with pulmonary fibrosis.
TEK (also known as Tie-2) is another receptor tyrosine kinase expressed only on endothelial cells which has been shown to play a role in angiogenesis. The binding of the factor angiopoietin-1 results in autophosphorylation of the kinase domain of TEK and results in a signal transduction process which appears to mediate the interaction of endothelial cells with peri-endothelial support cells, thereby facilitating the maturation of newly formed blood vessels. The factor angiopoietin-2, on the other hand, appears to antagonize the action of angiopoietin-1 on TEK and disrupts angiogenesis (Maisonpierre et al., Science, 1997, 277:55-60). Tie2 is up-regulated in tumor angiogenic vessels (Trogan, E. Br. J. Cancer, 1998, 77:51-56) and there is evidence that it may play a supportive role in hematopoietic cancers (L. Naldini et al., Cancer Cell, 2005, 8:211-226; Suda, T. et al., Cell, 2004, 118:149-161). In addition to its possible role in cancer, angiogenesis may also have implications in diseases like rheumatoid arthritis (RA), psoriasis and the progression of inflammation driven pathologies. The formation of pannus, the destructive legion responsible for arthritic progression is in part driven by new blood vessel formation and a recent paper by Lin, C. et al. (Arthritis and Rheumatism, 2005, 52(5):1585-1594) demonstrates the pathological role of Tie2 in a mouse collagen-induced arthritis models of RA. Therefore, inhibition of Tie2 could provide a beneficial effect against proliferative and inflammatory diseases.
Several other kinases have been implicated in the progression of proliferative diseases such as cancer. Among these, numerous Src family member proteins have been shown to play a similar role as Src and may provide parallel signaling pathways during uncontrolled cellular proliferation. Primary examples include the tyrosine kinases Lyn, Fyn, Lck and Hck. Lyn and Hck have been implicated in the progression of B-cell acute lymphoblastic leukemia (B-ALL), a hematopoietic cancer of B cells (Li, S. et al. Nat Genet., 2004 36(5):453-461).
The Eph (erythropoietin-producing hepatoma amplified sequence) family of tyrosine kinase receptors binds ephrins which leads to numerous cellular processes. Ephs appear to play a role modulating tumour cell adhesion and motility and invasiveness, and some evidence demonstrates an active role of Ephs and ephrins in neo-vascularisation during pathological processes. The Eph A receptors are over-expressed in lung, kidney and gastric tumour vasculature, and dominant-negative, soluble EphA2 or A3 proteins have been shown to modulate tumour angiogenesis and progression in vivo (Lackmann M. et al., IUBMB Life, 2005, 57(6):421-31).
Vascular endothelial growth factors and their cognate receptors, for example KDR (VEGFR2) and FLT1 (VEGFRR1) are key regulators of angiogenesis. The protein therapeutic drug AVASTIN® has shown promise in colon cancer and works through the VEGFR pathway. SUTENT/SU11248 (sunitinib malate) (Pfizer) is a potent KDR inhibitor and has shown promising results against GIST and renal cell carcinomas.
Peripheral blood monocytes (PBMCs) have been shown to express and secrete pro-inflammatory cytokines when stimulated with lipopolysaccharide (LPS) in vitro. P38 inhibitors efficiently block this effect when PBMCs are pretreated with such compounds prior to stimulation with LPS (Lee, J. C., et al., Int. J. Immunopharmacol., 1988, 10:835-843). The efficacy of p38 inhibitors in animal models of inflammatory disease has prompted an investigation of the underlying mechanism(s) which could account for the effect of these inhibitors. The role of p38 in the response of cells to IL-1 and TNF has been investigated in a number of cells systems relevant to the inflammatory response using a pyridinyl imidazole inhibitor: endothelial cells and IL-8 (Hashimoto, S., et al., J. Pharmacol. Exp. Ther., 2001, 293:370-375), fibroblasts and IL-6/GM-CSF/PGE2 (Beyaert, R., et al., EMBO J., 1996, 15:1914-1923), neutrophils and IL-8 (Albanyan, E. A., et al., Infect. Immun., 2000, 68:2053-2060) macrophages and IL-1 (Caivano, M. and Cohen, P., J. Immunol., 2000, 164:3018-3025), and smooth muscle cells and RANTES (aruoka, S., et al., Am. J. Respir. Crit. Care Med., 1999, 161:659-668). The destructive effects of many disease states are caused by the over production of pro-inflammatory cytokines. The ability of p38 inhibitors to regulate this overproduction makes them excellent candidates for disease modifying agents. Known inhibitors of p38 MAPK are active in a variety of widely recognized disease models. Inhibitors of p38 MAPK show positive effects in a number of standard animal models of inflammation including rat collagen-induced arthritis (Jackson, J. R., et al., J. Pharmacol. Exp. Ther., 1998, 284:687-692); rat adjuvant-induced arthritis (Badger, A. M., et al., Arthritis Rheum., 2000, 43:175-183; Badger, A. M., et al., J. Pharmacol. Exp. Ther., (1996) 279:1453-1461); and carrageenan-induced paw edema in the mouse Nishikori, T., et al., Eur. J. Pharm., 2002, 451:327-333). Molecules that block the function of p38 have been shown to be effective in inhibiting bone resorption, inflammation, and other immune and inflammation-based pathologies in these animal models.
Thus, a safe and effective kinase inhibitor would provide a means to treat debilitating diseases that can be regulated by modulation of one or more kinases.
International patent application publication number WO 2004/078116 discloses certain compounds as kinase inhibitors. Amongst these compounds are certain N1-substituted indazole derivatives having a substituent at the 5-position that contains a pyrazol-5-ylurea group. Examples of such compounds include the compounds of Examples 94 and 138 in which the N1 substituent is respectively a methyl group and a 2-hydroxy-2-methylpropyl group.
It has now been found that compounds having particularly desirable properties may be obtained by selecting the primary alcohol group, —CH2CH2OH, as the N1 substituent, and a particular substituent at the 5-position containing a 3-tert-butyl-1-p-tolyl-1H-pyrazol-5-yl group.